2 stroke 49cc speed question



bilboby

Member
Joined
May 14, 2010
Messages
104
Hi their,

Well i'm 230lbs and riding a 49cc rear friction drive engine & have reached 20mph but it's a new engine + it's forever having niggley problems. I should point out that before i needed to peddle for uphill riding but with the friction engine now fitted such rides are a an uphill riders dream as one peddles less harder.

Cheers & 73's
 
5

5-7HEAVEN

Guest
I weigh the same as you and cruise at 35mph.

It is not a simple question.
 

motorpsycho

Active Member
Joined
Aug 5, 2009
Messages
2,252
i'm 5'7, weigh 155 lbs, and my 49 cc 2 stroke is mounted to a 20" frame with 20" wheels and a 41 tooth sprocket.
I can get 25-28 mph top speeds out of it, but it also has an expansion chamber, a high flow air filter, an ngk spark plug, a re-jetted carb. and upgraded spark plug wire.
my top speed is limited because of my wheel / sprocket size, but 25 mph is pretty darn fast on a 20" bike.
i also have an 80 c.c. 2 stroke, also on a 20" bike with 20" wheels, and a 41 tooth sprocket. I am getting right around 27 mph out of it, and it has a modified stock (long pipe) exhaust, high flow air filter, cns style carb that i re-jetted, upgraded spark plug wire, and an ngk spark plug.
this engine is on an occ chopper, and the rear tire is 24" tall, as opposed to the rear cheater slick tire that's on my other bike, which is 21" tall. even tho both bikes have 20" rims and 41 tooth sprockets, the taller tire on my occ bike is giving me a tiny bit more top speed. in reality, the 49 cc and the 80 c.c. make about the same power (in my opinion), but the 49 cc seems to rev slightly faster, and higher than the 80 c.c., but the 80 c.c. seems to have more bottom end torque.
my next change to both bikes is going to be a 36 tooth sprocket because the 41 tooth sprockets are still too big. I can cruise easy at 15 mph right now without either engine revving super high, but at top speed, both engines rev higher than i'd like them to.
 

geebt48cc

Member
Joined
Feb 2, 2010
Messages
683
See, that's the reason I went with the 48cc, cause it's legal, and overall does the job.Uno, for a man that weighs 250+, it really holds it's own for a china made 48cc. It's got a slant head, but I'm interested in the bullet head.

Do you guys know where I would find one for a 48cc Skyhawk?

lol, I probably look like a hippo on this little bike, but who cares..........FUN is what it's all about for very little $$$$$$...........:eek:

Glen
 
5

5-7HEAVEN

Guest
If you want improved acceleration and a longer-lasting engine, nothing comes close to a shift kit.

No second chain/tensioner/rear sprocket issues.

And then there's shifting thru 7 gears!:D

NOTHING on the MB can match that sensation for me!:D

Well, maybe starting the engine and the bike slowly rolling forward.:cool:
 

HeadSmess

Well-Known Member
Joined
May 17, 2010
Messages
3,033
ok, heres the mathematical way.

1 hp= 30,000ft/lbs /min

or. move 1 pound 30,000 feet in a minute.

this doesnt take into account wind resistance, friction, or inertia.

so could be bs :p

um. it really depends on what engine it is.... cus if you have ever jumped on a ktm 50.... thats 49cc of pure evil :eek: that will quite easily get 100kg going at 90km/h...
 

motorpsycho

Active Member
Joined
Aug 5, 2009
Messages
2,252
ok, heres the mathematical way.

1 hp= 30,000ft/lbs /min

or. move 1 pound 30,000 feet in a minute.

this doesnt take into account wind resistance, friction, or inertia.

so could be bs :p

um. it really depends on what engine it is.... cus if you have ever jumped on a ktm 50.... thats 49cc of pure evil :eek: that will quite easily get 100kg going at 90km/h...
yes, a ktm 50 is a monster, but a portion of that has to do with the gearing in the transmission and the final drive gear ratio.
but, the ktm 50's make a ton more power than these little chinese motors ever will.
 
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